Ecological processes in arid lands are often described by the pulse-reserve paradigm, in which rain events drive biological activity until moisture is depleted, leaving a reserve. This paradigm is ...frequently applied to processes stimulated by one or a few precipitation events within a growing season. Here we expand the original framework in time and space and include other pulses that interact with rainfall. This new hierarchical pulse-dynamics framework integrates space and time through pulse-driven exchanges, interactions, transitions, and transfers that occur across individual to multiple pulses extending from micro to watershed scales. Climate change will likely alter the size, frequency, and intensity of precipitation pulses in the future, and arid-land ecosystems are known to be highly sensitive to climate variability. Thus, a more comprehensive understanding of arid-land pulse dynamics is needed to determine how these ecosystems will respond to, and be shaped by, increased climate variability.
The global reach of human activities affects all natural ecosystems, so that the environment is best viewed as a social-–ecological system. Consequently, a more integrative approach to environmental ...science, one that bridges the biophysical and social domains, is sorely needed. Although models and frameworks for social-–ecological systems exist, few are explicitly designed to guide a long-term interdisciplinary research program. Here, we present an iterative framework, "“Press-–Pulse Dynamics"” (PPD), that integrates the biophysical and social sciences through an understanding of how human behaviors affect "“press"” and "“pulse"” dynamics and ecosystem processes. Such dynamics and processes, in turn, influence ecosystem services -–thereby altering human behaviors and initiating feedbacks that impact the original dynamics and processes. We believe that research guided by the PPD framework will lead to a more thorough understanding of social-–ecological systems and generate the knowledge needed to address pervasive environmental problems.
Transit timing variations (TTVs) can be a very efficient way of constraining masses and eccentricities of multi-planet systems. Recent measurements of the TTVs of TRAPPIST-1 have led to an estimate ...of the masses of the planets, enabling an estimate of their densities and their water content. A recent TTV analysis using data obtained in the past two years yields a 34 and 13% increase in mass for TRAPPIST-1b and c, respectively. In most studies to date, a Newtonian
N
-body model is used to fit the masses of the planets, while sometimes general relativity is accounted for. Using the Posidonius
N
-body code, in this paper we show that in the case of the TRAPPIST-1 system, non-Newtonian effects might also be relevant to correctly model the dynamics of the system and the resulting TTVs. In particular, using standard values of the tidal Love number
k
2
(accounting for the tidal deformation) and the fluid Love number
k
2
f
(accounting for the rotational flattening) leads to differences in the TTVs of TRAPPIST-1b and c that are similar to the differences caused by general relativity. We also show that relaxing the values of tidal Love number
k
2
and the fluid Love number
k
2
f
can lead to TTVs which differ by as much as a few 10 s on a 3−4-yr timescale, which is a potentially observable level. The high values of the Love numbers needed to reach observable levels for the TTVs could be achieved for planets with a liquid ocean, which if detected might then be interpreted as a sign that TRAPPIST-1b and TRAPPIST-1c could have a liquid magma ocean. For TRAPPIST-1 and similar systems the models to fit the TTVs should potentially account for general relativity, for the tidal deformation of the planets, for the rotational deformation of the planets, and to a lesser extent for the rotational deformation of the star, which would add up to 7 × 2 + 1 = 15 additional free parameters in the case of TRAPPIST-1.
Analog methods (AMs) have long been used for precipitation prediction and climate studies. However, they rely on manual selections of parameters, such as predictor variables and analogy criteria. ...Previous work showed the potential of genetic algorithms (GAs) to optimize most of the AM parameters. This research goes one step further and investigates the potential of GAs for automating the selection of the input variables and the analogy criteria (distance metric between two data fields) in AMs. Our study focuses on the prediction of daily precipitation in central Europe, specifically Switzerland, as a representative case. Comparative analysis against established methods demonstrates the superiority of GA‐optimized AMs in terms of predictive accuracy. The selected input variables exhibit strong associations with key meteorological processes that influence the generation of precipitation. Further, we identify a new analogy criterion inspired by the Teweles‐Wobus criterion, which consistently performs better than other Euclidean distances and could be used in classic AMs. In contrast to conventional stepwise selection approaches, GA‐optimized AMs display a preference for a flatter structure characterized by a single level of analogy and an increased number of variables. Overall, our study demonstrates the successful application of GAs in automating input variable selection for AMs, with potential implications for application in diverse locations and data exploration to predict alternative predictands. In a broader context, GAs could be used to perform input variable selection in other data‐driven methods, opening perspectives for a broad range of applications.
Plain Language Summary
Analog methods (AMs) predict precipitation by searching for similar past meteorological situations. However, setting up these methods requires manual selection of meteorological variables and how to compare them. Genetic algorithms (GAs) can already optimize some of AM parameters, and our study goes further to explore whether GAs can automatically select the variables and comparison metrics. Our results indicate that AMs improved by GAs outperform other AMs in predicting rainfall. The chosen variables strongly relate to important weather processes influencing rainfall. We also identified a new criterion for measuring the similarity of meteorological situations, which outperforms others used in traditional methods. Unlike conventional stepwise approaches, GAs prefer a simpler structure with a single level of analogy. In summary, our study demonstrates that GAs simplify the process of choosing variables for AMs, with potential applications in various locations and data exploration for local weather prediction. Additionally, such approaches can be extended to select relevant variables in other data‐driven methods.
Key Points
Genetic algorithms were successful in selecting relevant input variables for the prediction of precipitation by analog methods
The analogy criteria were automatically selected, resulting in the discovery of a new promising criterion
The optimization resulted in a structure combining different predictors into a single level of analogy, while outperforming stepwise methods
ABSTRACT
The moons of giant planets are believed to form in situ in circumplanetary discs (CPDs). Here, we present an N-body population synthesis framework for satellite formation around a ...Jupiter-like planet, in which the dust-to-gas ratio, the accretion rate of solids from the protoplanetary disc, the number, and the initial positions of protosatellites were randomly chosen from realistic distributions. The disc properties were from 3D radiative simulations sampled in 1D and 2D grids and evolved semi-analytically with time. The N-body satellitesimals accreted mass from the solid component of the disc, interacted gravitationally with each other, experienced close-encounters, both scattering and colliding. With this improved modeling, we found that only about $15{{\ \rm per\ cent}}$ of the resulting population is more massive than the Galilean one, causing migration rates to be low and resonant captures to be uncommon. In 10 per cent of the cases, moons are engulfed by the planet, and 1 per cent of the satellite-systems lose at least 1 Earth-mass into the planet, contributing only in a minor part to the giant planet’s envelope’s heavy element content. We examined the differences in outcome between the 1D and 2D disc models and used machine learning techniques (Randomized Dependence Coefficient together with t-SNE) to compare our population with the Galilean system. Detecting our population around known transiting Jupiter-like planets via transits and TTVs would be challenging, but $14{{\ \rm per\ cent}}$ of the moons could be spotted with an instrumental transit sensitivity of 10−5.
On May 21, 2019 at 03:02:29 UTC Advanced LIGO and Advanced Virgo observed a short duration gravitational-wave signal, GW190521, with a three-detector network signal-to-noise ratio of 14.7, and an ...estimated false-alarm rate of 1 in 4900 yr using a search sensitive to generic transients. If GW190521 is from a quasicircular binary inspiral, then the detected signal is consistent with the merger of two black holes with masses of 85_{-14}^{+21} M_{⊙} and 66_{-18}^{+17} M_{⊙} (90% credible intervals). We infer that the primary black hole mass lies within the gap produced by (pulsational) pair-instability supernova processes, with only a 0.32% probability of being below 65 M_{⊙}. We calculate the mass of the remnant to be 142_{-16}^{+28} M_{⊙}, which can be considered an intermediate mass black hole (IMBH). The luminosity distance of the source is 5.3_{-2.6}^{+2.4} Gpc, corresponding to a redshift of 0.82_{-0.34}^{+0.28}. The inferred rate of mergers similar to GW190521 is 0.13_{-0.11}^{+0.30} Gpc^{-3} yr^{-1}.
Heterologous prime/boost regimens have the potential for raising high levels of immune responses. Here we report that DNA priming followed by a recombinant modified vaccinia Ankara (rMVA) booster ...controlled a highly pathogenic immunodeficiency virus challenge in a rhesus macaque model. Both the DNA and rMVA components of the vaccine expressed multiple immunodeficiency virus proteins. Two DNA inoculations at 0 and 8 weeks and a single rMVA booster at 24 weeks effectively controlled an intrarectal challenge administered 7 months after the booster. These findings provide hope that a relatively simple multiprotein DNA/MVA vaccine can help to control the acquired immune deficiency syndrome epidemic.
Headwater streams remove, transform, and store inorganic nitrogen (N) delivered from surrounding watersheds, but excessive N inputs from human activity can saturate removal capacity. Most research ...has focused on quantifying N removal from the water column over short periods and in individual reaches, and these ecosystem-scale measurements suggest that assimilatory N uptake accounts for most N removal. However, cross-system comparisons addressing the relative role of particular biota responsible for incorporating inorganic N into biomass are lacking. Here we assess the importance of different primary uptake compartments on reach-scale ammonium (NH₄⁺-N) uptake and storage across a wide range of streams varying in abundance of biota and local environmental factors. We analyzed data from 17 ¹⁵N-NH₄⁺ tracer addition experiments globally, and found that assimilatory N uptake by autotrophic compartments (i.e., epilithic biofilm, filamentous algae, bryophytes/macrophytes) was higher but more variable than for heterotrophic microorganisms colonizing detrital organic matter (i.e., leaves, small wood, and fine particles). Autotrophic compartments played a disproportionate role in N uptake relative to their biomass, although uptake rates were similar when we rescaled heterotrophic assimilatory N uptake associated only with live microbial biomass. Assimilatory NH₄⁺-N uptake, either estimated as removal from the water column or from the sum uptake of all individual compartments, was four times higher in open- than in closed-canopy streams. Using Bayesian Model Averaging, we found that canopy cover and gross primary production (GPP) controlled autotrophic assimilatory N uptake while ecosystem respiration (ER) was more important for the heterotrophic contribution. The ratio of autotrophic to heterotrophic N storage was positively correlated with metabolism (GPP:ER), which was also higher in open- than in closed-canopy streams. Our analysis shows riparian canopy cover influences the relative abundance of different biotic uptake compartments and thus GPP:ER. As such, the simple categorical variable of canopy cover explained differences in assimilatory N uptake among streams at the reach scale, as well as the relative roles of autotrophs and heterotrophs in N storage. Finally, this synthesis links cumulative N uptake by stream biota to reach-scale N demand and provides a mechanistic and predictive framework for estimating and modeling N cycling in other streams.
The Child Feeding Questionnaire (CFQ) is a self-report measure to assess parental beliefs, attitudes, and practices regarding child feeding, with a focus on obesity proneness in children. ...Confirmatory factor analysis tested a 7-factor model, which included four factors measuring parental beliefs related to child's obesity proneness, and three factors measuring parental control practices and attitudes regarding child feeding. Using a sample of 394 mothers and fathers, three models were tested, and the third model confirmed an acceptable fit, including correlated factors. Internal consistencies for the seven factors were above 0·70. With minor changes, this same 7-factor model was also confirmed in a second sample of 148 mothers and fathers, and a third sample of 126 Hispanic mothers and fathers. As predicted, four of the seven factors were related to an independent measure of children's weight status, providing initial support for the validity of the instrument. The CFQ can be used to assess aspects of child-feeding perceptions, attitudes, and practices and their relationships to children's developing food acceptance patterns, the controls of food intake, and obesity. The CFQ is designed for use with parents of children ranging in age from about 2 to 11 years of age.
Prophylactic vaccines against Epstein-Barr virus (EBV) are under development. EBV-naïve college freshmen are ideal candidates for an efficacy trial, because their incidence of infectious ...mononucleosis (mono) during freshman year is as high as 20%. To assess perceptions about mono and a mono vaccine, and to learn if EBV immune status could be determined using a gingival swab rather than phlebotomy, we performed a cross-sectional study of 235 healthy students at the beginning of their freshman year. Subjects completed questionnaires and donated oral washes, gingival swabs and venous blood. Overall, 90% of students found the swab easy to use and 80% preferred the swab over venepuncture. Of the 193 students with sufficient samples, 108 (56%) had EBV antibodies in blood vs. 87 (45.1%) in the gingival swab. The sensitivity and specificity of the swab compared with blood for detecting EBV antibodies was 75.9% and 94.1%, respectively, with an accuracy of 89.3%. EBV DNA was detected in the oral wash and swab of 39.2% and 30.4% of blood-antibody-positive individuals, respectively. In conclusion, 44% of our freshmen were EBV-naïve and thus vaccine candidates, the gingival swab was an acceptable alternative to phlebotomy for detecting EBV antibody but needs improved sensitivity, and the perceived value of EBV vaccine was high (72% believed they would benefit).
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